Investments in Marketable Securities with Unrealized Losses (Detail) (USD $) In Millions, unless otherwise specified	Jun. 28, 2013
Schedule of Available-for-sale Securities [Line Items]
Unrealized Loss Less than 12 months, Fair Value	$ 174.7
Unrealized Loss Less than 12 months, Unrealized Loss	(2.8)
Unrealized Loss Greater than 12 months, Fair Value
Unrealized Loss Greater than 12 months, Unrealized Loss
Total, Fair Value	174.7
Total, Unrealized Loss	(2.8)
U.S. government debt obligations
Schedule of Available-for-sale Securities [Line Items]
Unrealized Loss Less than 12 months, Fair Value	41.0
Unrealized Loss Less than 12 months, Unrealized Loss	(0.8)
Unrealized Loss Greater than 12 months, Fair Value
Unrealized Loss Greater than 12 months, Unrealized Loss
Total, Fair Value	41.0
Total, Unrealized Loss	(0.8)
Corporate debt obligations
Schedule of Available-for-sale Securities [Line Items]
Unrealized Loss Less than 12 months, Fair Value	51.6
Unrealized Loss Less than 12 months, Unrealized Loss	(0.5)
Unrealized Loss Greater than 12 months, Fair Value
Unrealized Loss Greater than 12 months, Unrealized Loss
Total, Fair Value	51.6
Total, Unrealized Loss	(0.5)
Mortgaged backed debt obligations guaranteed by GNMA
Schedule of Available-for-sale Securities [Line Items]
Unrealized Loss Less than 12 months, Fair Value	82.1
Unrealized Loss Less than 12 months, Unrealized Loss	(1.5)
Unrealized Loss Greater than 12 months, Fair Value
Unrealized Loss Greater than 12 months, Unrealized Loss
Total, Fair Value	82.1
Total, Unrealized Loss	$ (1.5)